1. Field of the Invention
This invention relates to the field of non-manual handling of fragile articles, particularly silicon and like wafers utilized in the manufacture of semiconductor devices in the electronics industry. More particularly, this invention relates to the field of automatic feeding, pre-aligning, mask aligning and exposing silicon wafers during a semiconductor device manufacturing procedure.
Still more particularly, this invention relates to the field of improved means for automatically discharging silicon wafers in sequence from a supply magazine, automatically prealigning the same prior to introducing the same to a treating station, such as a mask aligner, followed by automatic discharge of the treated wafers to a wafer receiving station.
In its broader aspects, this invention relates to means and procedures for non-manual handling of articles of various types, particularly flat fragile articles, and for performing orientation functions on such articles in sequence, such as by locating a flat edge of each such article in predetermined orientation in accordance with a predetermined plan.
In its more specific aspects, this invention relates to the field of improved fluid bearing handling and preorientation systems and procedures for silicon and like wafers utilized in the electronics industry in the manufacture of integrated circuits, transistors and like semiconductor devices.
2 Description of the Prior Art
In the electronics industry, apparatus and procedures for manufacturing semiconductor devices which utilize a series of steps involving depositing or diffusing layers of materials on or into silicon or like wafers is well known. Following such diffusion or deposit, selective areas of the diffused or deposited material are removed by well known processes in a series of steps to produce large numbers of semiconductor devices from a single treated wafer. Such procedures utilize well known mask alignment steps which photographically print a pattern from a mask of predetermined design onto a previously photoresist coated wafer. The steps of photoresist coating and mask aligning are generally well known in the art and various mask alignment apparatus and methods are known and commercially available at the present time. Characteristic of such mask alignment apparatus and wafer handling procedures in mask aligning methods are the apparatus and procedure illustrated in Tancredi U.S. Pat. Nos. 3,521,953 and 3,521,955, both dated July 28, 1970.
The mask alignment apparatus and procedures illustrated and disclosed in said Tancredi patents include a pre-alignment procedure by means of which silicon wafers to be mask aligned are preliminarily oriented so that the flat edge commonly provided on such wafers to assist in pre-alignment thereof is located in a particular position. However, with procedures of the type illustrated in said Tancredi patents, and in other known pre-alignment procedures, pre-alignment is effected substantially entirely manually by the operator. That is, wafers to be pre-aligned and subsequently mask aligned are handled manually.
With such prior known pre-alignment and mask aligning apparatus and procedures, of the type of which the Tancredi patents are illustrative, time consuming and delicate manual operations are required which necessitate the utilization of trained personnel.
The apparatus and method of this invention has been specially designed to obviate the need for manual handling of wafers during feeding of the same into a pre-alignment station, during pre-alignment thereof, and during subsequent mask alignment and discharge thereof from the mask alignment station. That is, with the present invention a fully wafer automatic feeding and pre-aligning system is provided which virtually eliminates all manual operations in conjunction with mask alignment of wafers in the production of semiconductor devices. In that regard, the only manual operation required is the loading of wafer carrying magazines at a sender or feed station and the unloading of wafer carrying discharge magazines at a discharge or receiver station. In other respects, the apparatus and method of this invention is fully automatic with respect to feeding, pre-alignment and discharging from a mask aligner apparatus.
Depending upon the type of mask aligner apparatus with which the subject feeding and pre-alignment system is utilized, some manual checking or manipulation during the actual mask aligning operation may be employed. However, alternatively, the subject invention may be utilized with automatic mask aligning procedures which, when utilized, completely obviate the need for any manual handling even during mask alignment, so that a fully automated system is produced once a supply of silicon wafers is positioned in a carrier at a sender station.
While this invention has particular utility in conjunction with the handling and pre-alignment of fragile articles such as silicon wafers, it should be understood also that its utility in other related areas also is contemplated and should be included within the scope of the inventive concepts disclosed herein.
The numerous advantageous features of this invention are incorporated into a compact apparatus which is readily adaptable for use in combination with known mask alignment apparatus and systems such as those characterized by the Tancredi patents noted above. So far as is known, the improved wafer handling and pre-alignment system and procedure disclosed herein is novel